High switching frequency, high efficiency CLL resonant converter with synchronous rectifier

In this paper, a CLL resonant tank (CLL) is presented as an attractive option in the front-end applications as DC/DC converter. This topology can achieve zero-voltage switching (ZVS) from zero load to full load, low turn off loss, ZCS for output rectifier, and easy to realize secondary rectification. A novel design methodology of CLL resonant converter is proposed based on the trade-off among efficiency, hold up time and ZVS requirement. A transformer structure for better performance in high frequency application is proposed. And current type synchronous rectifier (SR) drive scheme is used in this topology. An 800 kHz, 300 W CLL resonant converter prototype is made to verify the proposed design method.